fig6

Figure 6. Digital photographs of the residues after cone calorimeter testing: side views of (A) PHE, (B) PHAE, and (C) PHHE; top views of (D) PHE, (E) PHAE, and (F) PHHE; SEM images of the char residues of (G) PHE, (H) PHAE, and (I) PHHE; and (J) schematic illustration of the flame-retardant mechanism. PEG: Polyethylene glycol; HDI: hexamethylene diisocyanate; APP: ammonium polyphosphate; EG: expanded graphite; HAPP: hydroxylated ammonium polyphosphate; PHE: PEG/HDI/EG; PHAE: PEG/HDI/APP/EG; PHHE: PEG/HDI/HAPP/EG; SEM: scanning electron microscopy; PH: PEG/HDI; PHH: PEG/HDI/HAPP.